Horrible. Randomly issued.
U.S. Census Bureau: FAQs
Do I have to respond to the American Community Survey / Puerto Rico Community Survey? Yes. Respondents are required to answer all questions on the American Community Survey (ACS) to the best of their ability. Response to this and other Census surveys is required by law (Section 221 of Title 13, Chapter 7, United States Code). This chapter also contains information regarding offenses and possible penalties. According to Section 221, persons who do not respond shall be fined not more than $100. Title 18 U.S.C. Section 3571 and Section 3559, in effect amends Title 13 U.S.C. Section 221 by changing the fine for anyone over 18 years old who refuses or willfully neglects to complete the questionnaire or answer questions posed by census takers from a fine of "not more than $100" to "not more than $5,000."
“http://codes.lp.findlaw.com/uscode/13/7/II/221"
“(c) Notwithstanding any other provision of this title, no person shall be compelled to disclose information relative to his religious beliefs or to membership in a religious body.”